e i ith sbr d sbs difi dexperiences with sbr and sbs ... presentation.pdfmodified bitumen usage in...
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E i ith SBR d SBS difi dExperiences with SBR and SBS modified binders in the construction of seals in RSA
JG L /TR Di tiJG Louw/TR Distin
Cost effective high performance surfacingsperformance surfacings
Overview
f f• Use of modified binders in RSA• Properties of SBR and SBS modified binders• Storage stability during handling• Storage stability during handling• Application techniques for spray seals • Design of modified binder spray sealsDesign of modified binder spray seals• Summary
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Modified bitumen usage in Sealsg
• < 1982 - mainly SBR and natural latex in anionic emulsions• 1982 Bitumen rubber• 1982 - Bitumen-rubber • 1984 - SBR latex in hot bitumen• 1989 - SBR latex in cationic emulsions• 1990 - SBS polymer in hot bitumen
44%8%16% penetration
cutbackemulsion
2%10%20%
SBSSBRRubber
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SBS block co-polymer
Ordered molecular structure
SBR (latex)
Random molecular structureRandom molecular structure
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= styrene = butadiene
P l t d i
Polystyrenedomain
Polystyrene domain
Butadiene chain
Butadienechains
B h d SBSLinear SBS Branched SBS
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Softening Point of SBR vs SBSg(80/100 pen base bitumen)
110
90
100
(deg
C)
60
70
80
ning
Poi
nt
SBS
SBR
40
50
60
0 1 2 3 4 5
Softe
0 1 2 3 4 5
Polymer content (%m/m)
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Viscosities – SBR vs SBS(80/100 pen base bitumen)
900
600
700
800
mPa
.s)
3% SBR
200
300
400
500
Vis
cosi
ty (m
3% SBS80/100
0
100
200
130 140 150 160 170 180 190 200 210
V
130 140 150 160 170 180 190 200 210
Temperature (deg C)
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Elastic Recovery – SBR vs SBS y(80/100 pen base bitumen)
90
75808590
deg
C (%
)
60657075
over
y @
15
3% SBR
3% SBS
40455055
last
ic R
eco
405 10 15 20
Temperature (deg C)
El
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1 40
1.60
0.80
1.00
1.20
1.40
sion
J/c
m2
3% SBR
80/100 Cohesion
0.00
0.20
0.40
0.60
Coh
es 3% SBS properties
@ 5°C
Tensile Properties – NF EN 13587
10 20 30 35 40 45 50 60
Temperature (deg C)
Tensile Properties NF EN 13587Initial length = 50 mm
Unit 80/100 3% SBR in 80/100
3% SBS in 80/100
At break:At break:ElongationStress
%MPa
3390,06
>9000,59
>9000,68
Deformation Energy Properties – NF EN 13703
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o o gy op s 3 03At break:
Mean energy J/cm2 9,6 24,1 29,1
Storage Stability at application g y pptemperature
70
Ring and Ball Softening Point
1200
Dynamic Viscosity
10203040506070
& B
Sof
t Poi
nt
(deg
C)
SBR (200 deg C)SBS (180 deg C)
0200400600800
10001200
Visc
osity
@ 1
35
deg
C (m
Pa.s
)
SBR (200 deg C)SBS (180 deg C)
010
R &
0 5 11 13 16 18
Time after manufacture (hrs)
0V
0 5 11 13 16 18
Time after manufacture (hrs)
4050607080
ecov
ery
g C
(%)
Elastic Recovery
010203040
Elas
tic R
e@
15
deg
0 5 11 13 16 18
Time after manufacture (hrs)
SBR (200 deg C)SBS (180 deg C)
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( )
Typical modified binder seals yp
Single Seal Double Seal
EXISTING SUBSTRATE EXISTING SUBSTRATE
Split Seal Cape Seal
EXISTING SUBSTRATE EXISTING SUBSTRATE
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Typical application rates
Aggregate
Single seal 13,2 mm aggregate (ALD = 8,2)
Traffic (ELV)5000 1000 > 20000 Spread
rate (m3/m2)
Bi d li ti t (l/ 2) h tBinder application rate (l/m2) hot
3% SBR + 80/100 1,65 1,24 1,15 90 – 100
3% SBS + 80/100 1,78 1,34 1,20 90 – 100
Cationic Spray Grade 70% + 5% latex 1,68 1,27 1,13 90 – 100
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5% latex
Spray rate ajustment factors – TRH 3p y j
SBR modified bitumen
T ffi ( l ’ ) Si l S l D bl S l S li S lTraffic (elv’s) Single Seal Double Seal Split Seal
< 5000 1,3 1,1 1,2
5000 – 20000 1,2 1,0 1,15000 0000 , ,0 ,
> 20000 1,1 1,0 1,0
SBS modified bitumen
< 5000 1,4 1,2 1,3
5000 – 20000 1,3 1,1 1,2
> 20000 1,2 1,0 1,1> 20000 1,2 1,0 1,1
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Construction of seals
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Use of cutters
• General resistance amongst practitioners• No cutters allowed on National Route contracts
When used with discretion excellent results• When used with discretion – excellent results• Generally not more than 4% cutter used• Cutback SBR marginally less temperature sensitive• Cutback SBR marginally less temperature sensitive
than SBS PMB’s
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Semi-priming polymer modified binderp g p y
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Summaryy
• With the increase in traffic and rapid ageing of the South African national & provincial road networkSouth African national & provincial road network have lead to 70% of all reseals being constructed using modified binders
• Practitioners recognise the improved life cycle costs associated with the use of these binders Th i d f ti f SBS• The improved performance properties of SBS vs SBR modified binders have resulted in an increase demand for SBS modified binders
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